The Comparative Effects of Pruning by Burning or Clipping on Lowbush Blueberries in North-Eastern Ontario

Abstract

The lowbush blueberries, especially Vaccinium angustifolium Ait. and its varieties and forms (Smith 1969), are widespread and abundant in most regions of north-eastern Ontario. Natural stands of these indigenous species may offer considerable potential as a commercial fruit crop in this region (Smith, Hilton & Evans 1968). Of the cultural practices used to improve natural stands of these plants pruning by burning is probably the most common. Burning on a 2 or 3 year basis to increase shoot growth and fruit production is the usual practice in regions presently producing lowbush blueberry fruit on a commercial scale (Eaton & White 1960). Also, burning evidently offers some advantage by partially removing competitive growth of other species and controlling certain insect pests but these effects are poorly documented. Black (1963) suggested that the short and long-term ecological effects of burning have not received sufficient investigation to justify the practice. The lack of knowledge of the effects of burning is particularly true for north-eastern Ontario which differs in climate and soil from the maritime regions of North America and Great Britain where the practice of burning has been studied (Allen 1964; Black 1963; Chapman 1967; Eaton & White 1960; Robertson & Davies 1965). Boultbee (1956) has reported increased blueberry foliage cover and fruit production as an immediate effect of burning at a northern Ontario location but accompanying soil changes were not considered. This paper reports on the effects on lowbush blueberries and associated species of pruning by two methods of burning and by mechanical clipping, on three dates in the growing season at a north-eastern Ontario location. Significant soil changes recorded during the study are included in this report. The paper forms part of a larger scale ecological study of the effects of burning and an evaluation of the potential of lowbush blueberries as a fruit crop in northern Ontario.